1. Technical Field
The present invention relates to a liquid ejecting head, a liquid ejecting unit, and a liquid ejecting apparatus.
2. Related Art
A circulation-type apparatus is known in the field of an ink-jet recording apparatus, which is an example of a liquid ejecting apparatus. In a known circulation-type ink-jet recording apparatus, for example, one disclosed in JP-A-2009-23289 (in particular, refer to FIG. 3), an ink tank is provided at a distance from an ink-jet recording head. Ink flows from the ink tank to the ink-jet recording head, and then back to the ink tank in a circulatory manner.
In the ink-jet recording apparatus disclosed in JP-A-2009-23289, a single tube on an outgoing channel and a single tube on a return channel are connected to the ink tank. A plurality of branch tubes is branched from the outgoing tube. Each of the outgoing branch tubes is connected to the corresponding one of a plurality of recording heads for supplying ink thereto. A plurality of branch tubes is branched from the return tube. Each of the return branch tubes is connected to the corresponding one of the plurality of recording heads for collecting ink therefrom. Each of the plurality of recording heads has a flow passage for circulation. With a circulatory flow, it is possible to suppress the precipitation of components in liquid while making it easier to let out air bubbles.
The ink-jet recording apparatus disclosed in JP-A-2009-23289 has the following problem. A filter that is provided in a filter chamber traps air bubbles. The trapped air bubbles cover the upper surface of the filter to clog it up completely, which obstructs the circulatory flow of ink. Because the circulation of ink is hampered, the print performance of the ink-jet recording apparatus decreases. The above problem is not unique to a liquid ejecting apparatus that is provided with an ink-jet recording head(s). That is, the same problem could also arise in various kinds of liquid ejecting apparatuses provided with a liquid ejecting head(s) for ejecting liquid, which is not limited to ink.